What was found
FLT 713 FROM DEN TO TOL. DURING CRUISE LEVEL, THE LOWER AFT CARGO FIRE WARNING LIGHT CAME ON INFLIGHT. APPROPRIATE CHECK LIST WERE ACCOMPLISHED, NOTIFIED ATC, DECLARED EMERGENCY AND AIR TURNBACK TO DEN AND LANDED WITHOUT INCIDENT. UPON LANDING INSPECTED THE LOWER AFT CARGO COMPARTMENT AND FOUND NO INDICATION OF FIRE. MEL THE LOWER AFT CARGO COMPARTMENT AREA DETECTION SYSTEM PER 26-19-1A. AIRCRAFT RETURNED TO SERVICE. MEL 26-19-1 WAS CLEARED UPON ARRIVAL IN TOL 8/29/2002 BY REPLACING A SMOKE DETECTOR AND TWO SMOKE DETECTOR BATTERIES.